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> are interoperable in Rust (block_on) Blocking an OS thread as a mean to be compatible is not exactly what we're trying to do here. > Except the performance

> are interoperable in Rust (block_on) Blocking an OS thread as a mean to be compatible is not exactly what we're trying to do here. > Except the performance difference between a kernel-mode context switch and a user-mode one is only going to narrow in the future OS overhead can be minimized, but program stacks are a function of the language's. And if you're not right sizing preemption points in your stack, you'll be switching large parts of it. This means you _must_ have stackful coroutines if you want to keep switching threads. > The real solution to expensive context switches is to just do fewer of them... No context switch is always faster than a "fast" context switch. Sure, but writing the perfect assembly and using gotos has always been the fastest. Abstraction has a cost, and some runtimes/languages are currently proving that they can reduce this cost to zero in the current conditions of IO being much costlier than a few 100s of nanos. We're just happening to be at a time where the compiler is starting to be smarter than the user. But I guess the benchmarks will settle all this. > Just look at this issue: https://marcan.st/2017/12/debugging-an-evil-go-runtime-bug/ https://marcan.st/2017/12/debugging-an-evil-go-runtime-bug/ So that's a bug in the go compiler. They can either fix it or pay a "a small speed penalty (nanoseconds)" as a workaround, which the author qualifies as "acceptable". Yes, that's not the absolute performance possible. But why care about that? At some point it all comes down to TCO (except for latencies in HFT); and TCO tells you that it's ok. Development complexity and maintainability matters. Especially when you can max out your IO usage for the decades to come.

Diggsey 6y ago
> Blocking an OS thread as a mean to be compatible is not exactly what we're trying to do here. It's what Go does whenever you call into a C function or make a system-call. As long as those blocking functions are not the bottleneck then it works fine. My problem with the "colored function" analogy is that it implies that the problem is somehow due to the surface syntax, when in reality the problem still exists in all languages that support procedural IO: some of those languages like to just pretend that the problem doesn't exist. The only language I'm aware of which truly solves that is Haskell, since all IO happens via a monad. > Yes, that's not the absolute performance possible. But why care about that? This point was not about performance. It's about the pitfalls of writing all of your code on top of a complex and buggy runtime. Programming is a lot simpler, and development is a lot faster, when I don't have to worry about that. There are also several things that are a lot more complicated when you bake a complex runtime into the language like Go does. Thread-local storage is completely broken for one. If you do any kind of GUI programming, you may need to use `runtime.LockOSThread` as most GUIs expect function calls from a single thread. etc. etc.

Diggsey 6y ago

> Blocking an OS thread as a mean to be compatible is not exactly what we're trying to do here. It's what Go does whenever you call into a C function or make a system-call. As long as those blocking functions are not the bottleneck then it works fine. My problem with the "colored function" analogy is that it implies that the problem is somehow due to the surface syntax, when in reality the problem still exists in all languages that support procedural IO: some of those languages like to just pretend that the problem doesn't exist. The only language I'm aware of which truly solves that is Haskell, since all IO happens via a monad. > Yes, that's not the absolute performance possible. But why care about that? This point was not about performance. It's about the pitfalls of writing all of your code on top of a complex and buggy runtime. Programming is a lot simpler, and development is a lot faster, when I don't have to worry about that. There are also several things that are a lot more complicated when you bake a complex runtime into the language like Go does. Thread-local storage is completely broken for one. If you do any kind of GUI programming, you may need to use `runtime.LockOSThread` as most GUIs expect function calls from a single thread. etc. etc.